Continuous gasoline warmup factor analyzer and method of control



April 23, 1968 w. H. PAGE CONTINUOUS GASOLINE WARMUP FACTOR ANALYZER AND METHOD oF CONTROL Filed sept. 30, 1965l 2 Sheets-Sheet l AWT 23, 196s Filed Sept. SO, 1965 W. CONTINUOUS GASO H. PAGE LINE WARMUP FACTOR ANALYZER AND METHOD oF CONTROL 2 Sheets-Sheet 2 BYWW Uni

This invention relates to an apparatus and method for continuously measuring the warmup factor of motor gasoline, and to a method of yblending gasoline and other volatile multicomponent liquids to predetermined warmup factors.

The performance of gasoline-fueled internal combustion engines is in part dependent on the volatilty of the gasoline fuel. A high volatility fuel is required for easy starting and satisfactory cold performance at engine temperatures below the normal operating level, yet it is the lower volatility constituents of the gasoline which afford increased power and higher mileage. These divergent requirements are satisfied 'by a gasoline blended from components of high, low and intermediate volatility, the quantity of each component being selected to afford balanced volatility to the blended gasoline. Thus, a preferred motor gasoline contains both high volatility constituents to promote starting and cold engine operation, and lower volatility constituents for improved performance under normal operating conditions.

The ASTM Engler distillation has long been an accepted method of characterizing volatile petroleum products such as motor' and aviation Lgasolines. This test is performed by slowly heating a measured quantity of test material in a standard test apparatus so as to vaporize the test material, the vapor being separately condensed and recovered. The distillation temperature and the quantity of distillate recovered are periodically observed. The test result can be reported either as percents evaporated at various temperatures or as temperatures at various per-cents evaporated. In either case, several corresponding percentages and temperatures must be reported to characterize any particular gasoline sufficiently to define its engine `warmup performance. This, coupled with the difficulty of calculating ASTM distillation points of a blended gasoline from the ASTM distillations of the individual components points out the need for a more simplified method of characterizing the warmup performance of a motor gasoline. Hence, the concept of warmup factor was developed to afford a simplified characterization of the starting and cold engine performance characteristic of motor gasolines.

Warmup factor is defined as the sum of the volume percents evaporated at 180 F., 210 F. and 250 F. as obtained by standard ASTM distillation. The numerical value of warmup factor is an indication of the relative volatility of the gasoline, and of its warmup characteristic in an internal combustion engine. The numerical values of warmup factor range from to 300' for any volatile -t aterial. A value of 0 represents a material which is nonvolatile at temperatures up to 250 F. and a value of 300 represents a material which is totally vaporized at 180 F. Most gasoline stocks are characterized by warmup factors having a numerical value intermediate between 0 and 300. Although the various blending stocks can have lwarmup values from 0' to 300, depending upon their respective volatilities, blended d States Patent O motor gasoline is usually characterized by a warmup factor within the narrow range of a-bout to about 160. For example, a typical gasoline which is 20% evaporated at F., 50% evaporated at 210 F., and 70% evaporated at 250 F. has a warmup factor of 140. Although the concept of warmup factor is primarily adapted to the characterization of motor gasoline, it can also eliicaciously be employed to characterize the volatility of any multicomponent volatile liquid.

The warmup factor specification of motor gasoline can be set depending on a number of factors, such as the quality level desired to be maintained for a particular grade of gasoline, the type of equipment in which the gasoline is primarily used, the percentage of market satisfaction desired, the geographical area in which the gasoline is distributed and the season of the year. The numerical value of the specification can be changed periodically to accommodate seasonal changes. The performance of a gasoline characterized by a warmup factor of any particular numerical value can be ascertained by road test of the gasoline under actual road conditions.

Conventionally, warmup factors of the various blend stocks are determined by laboratory analysis and an optimum composition calculated. The calculated composition can be verified by a laboratory or pilot blend simulating the proposed production composition. Adjustments in t-he composition can be made, if necessary. This method of predicting the quality of the finished product can be inaccurate, particularly where gasoline stocks are being concurrently produced into the blending stock tankage. 'Heretoford blending control was not so critical as the gasoline was blended into tankage and tested for quality. Necessary adjustments could then be made by adding additional components until a iinal product of the desired quality was attained, which was then available for shipment. However, with the advent of the continuous inline method of gasoline blending, the product gasoline is frequently produced directly into common carrier pipelines, tank ships, remote shipping tanks, etc., where product reblendin'g is impractical. Although the blended product can be sampled and analyzed from time to time during the blending operation, it is difficult to control the lquality etfectively by such spot sampling. Due to the increased -necessity of assuring that gasoline blended continuously meets specification, the closeness to which product specifications can be approached is limited.

Accordingly, a primary object of this invention is to provide means for continuously measuring the warmup factor of a multicomponent volatile liquid such as motor gasoline. A further object is to provide means for continuously measuring the warmup factor of a motor gasoline as the gasoline is blended. A still further object is to adapt these warmup factor measuring means to the continuous control of the warmup factor of a blended product. An additional object of this invention is to provide a continuous inline method of gasoline blending wherein the warmup factor of the blended product is controlled to a predetermined value. Other objects and advantages of the invention will be apparent from the following description and appendant drawings, of which:

FIGURE l is a schematic diagram, partly in crosssection, of the continuous warmup factor analyzing apparatus of this invention.

FIGURE 2 is a schematic llow diagram of a liquid blending system for the production of a blended product having a predetermined warmup factor.

According tothe method of this invention, the warmup factor of a multicornponentliquid mixture can be determined by performing three simultaneous, continuous, isothermal distillations of a sample of the liquid mixture, each distillation being made at a selected temperature, eg. at temperatures of 180 F., 210 F. and 250 F., so as to obtain an overhead and a residue fraction from each distillation. The ow rate of sample charged to each of the distillation steps is controlled equal. The volume flow rate of overhead and residue obtained from each of the distillations will vary depending upon the temperature at which the distillation is performed. The overhead products are combined to obtain a combined overhead product. The residue obtained from each of the distillation steps is similarly combined to obtain a combined residue. The volume flow rates of the combined overhead and combined residue are separately measured. In a preferred embodiment the overhead product is condensed prior to measurement of the volume flow rate of combined overhead. If desired, signals proportional to the volume ow rates of the combined overhead and combined residue can form the input to an analog computing device which calculates the warmup factor. The output of the analog computer can be employed to control the proportion of the various components in the blended prod-uct so as to produce a product having a predetermined warmup factor.

The warmup factor analyzing apparatus of this invention can best be described with reference to FIGURE 1, which is a schematic diagram illustrating a preferred embodiment of the apparatus. Referring now to FIGURE 1, the principal elements of the analyzing apparatus are distillation units 10, 30 and Sti, Each of these units is substantially identical in size and configuration. Distillation unit comprises housing 11 which defines enclosed, elongated chamber A in which the distillation is accomplished. Trays, packing, or similar` internal devices conventionally employed in distillation separations are unnecessary as a single searation without substantial reflux is desired. External reux and contacting materials are not employed to avoid rectification within the chamber, a single isothermal distillation stage being desired. Some minimal internal reux can result from condensation of vapors on the upper internal surface of the housing. Housing 11 is surrounded on the exterior by insulating material 12 to minimize this condensation and to afford isothermal conditions. Feed enters chamber A through line 13 which passes through insulating material 12 and connects to an opening in housing 11 so that line 13 is in iluid commuuication with chamber A. Liquid residue is withdrawn from the bottom of chamber A via line 14 and vapor is withdrawn from the top of the chamber via line 15, both lines being in communication with the chamber. Heat to accomplish the distillation is supplied by passing a hot fluid through heating coil 16 at a rate controlled by Valve 17 responsive to temperature controller 18'. The volume flow rate of feed to chamber A is controlled by valve 19 in line 13, which is responsive to ow controller 20. A liquid level is maintained within chamber A by means of liquid level controller 21 which actuates valve 22 located in line 14. Vapors withdrawn from chamber A via line are condensed in condenser 23 located in line 15. The volume ow rate of condensed overhead from distillation unit 10 is measured and recorded by iiow recorder 24. It is essential that condenser 23 be positioned so that condensed material will not ow from the condenser back through line 15 to chamber A. This is easily yaccomplished by positioning the condenser below the top of housing 11.

Similarly, distillation unit comprises housing 31 deiining enclosed, elongated chamber B and which is externally covered with insulating material 32. Feed is introduced into chamber B through line 33 and liquid residue withdrawn through line 34. Vapors are Withdrawn from the chamber via line 35. Heat is provided by heating coil 36 which has hot fluid passing Aerethrough at ,4 a rate controlled by valve 37 responsive to temperature controller 38. The feed rate to chamber B is controlled by valve 39 and ow controller 40 located in line 33. A liquid level is maintained within chamber B by liquid level controller d1 which actuates valve 42 in line 34. The overhead vapor from distillation unit 39 passes through condenser `43 in line 35 whereupon it is condensed. The volume tlow rate of condensed overhead is measured and recorded by ow recorder 44.

Also similarly, distillation unit 5t) comprises housing 51 defining enclosed, elongated chamber C and which is externally covered with insulating material 52. Feed is introduced into chamber C through line 53 and liquid residue withdrawn through line 54. Vapors are withdrawn from the chamber via line 55. Heat is supplied by passing a hot uid through heating coil 56 at a rate controlled by valve 57 responsive to temperature controller 58. The feed rate to chamber C is controlled by valve 59 and flow controller 60 located in line 53. A liquid level is maintained within chamber C by liquid level controller 61 which actuates valve 62 in line S4. The overhead vapor from distillation unit 50 passes through condenser 63 in line 55 whereupon it is condensed. The volume flow rate of condensed overhead is measured and recorded by tiow recorder 64, also in line 55. Either electric or pneumatic control modes, or combinations of electric and pneumatic modes, can be employed in the various control systems of the analyzer.

Although analyzers employed in the measurement of the warmup factor of motor gasolines are standardly adjusted to maintain distillation temperatures of F., 210 F. and 250 F., temperature controllers 18, 38 and 58 can be adjusted to maintain other temperatures where desired.

Feed lines 13, 33 and 53 lare connected to common sample feed line 70. lLiquid residue lines 14, 34 and 54 are connected to line 8) having liow meter 81 located therein at a point downstream of the junction of the individual residue lines. The volume flow rate of the net liquid residue is measured by flow meter 81 located in line 80. Flow meter 81 develops an analog output signal proportional to the volume ow rate of residue through line 80. Line S0 may discharge'to the suction of a pump or other low pressure reservoir. The residue withdrawal facilities must provide for disposal of the residue without increasing the pressure in the distillation chambers as it is essential that the distillation be performed at substantially atmospheric pressure.

Vapor lines 15, 35, and 55 communicate with line 82 having flow meter S3 located therein at a point downstream of the junction of the individual vapor lines. The volume flow rate of the net condensed overhead is measured by tlow meter 83 located in line 82. Flow meter 83 develops an analog output signal proportional to the volume flow rate of overhead product through line 82. Overhead product line 82 can discharge into an atmospheric or subatmospheric disposal in order that the operating pressure in the distillation chambers will remain at substantially atmospheric pressure. If desired, pressure control can be provided to maintain this pressure.

The analog output signals generated by flow meters 81 and 83 are transmitted to analog computer 84 by means of signal transmission lines S5 and 86, respectively. Computer 84 can be any analog device capable of simultaneously receiving a first analog input signal proportion-al to the volume iiow rate of net overhead and a second analog signal proportional to the volume flow rate of net residue and calculating the warmup factor from these input signals. `Warmup factor is calculated from the volume liow rates of net overhead and residue by the simple mathematical relationship:

where OH represents the volume ow rate of net over- Warmup Factor: 300 X head and R represents the volume flow rate of net residue. This calculation is accomplished by dividing the product of 300 times the first analog signal by the sum of the rst and second analog signals. Of course, the signals must be based on a common scale or appropriate additional factors included in the computation. The numerical value continuously computed from the above relationship is indicated as an output from computer 84 and represents the warmup factor based on the isothermal distillations. The output from computer d4 can be indicated, recorded and further used as the input signal to apparatus for controlling blend composition. In the apparatus of FIGURE 1, the output signal from computer 84 is recorded on warmup factor recorder 87. Suitable analog devices performing this function include pneumatic and electrical relays, force bridges, and the like. As previously stated, either pneumatic or electrical control systems can be employed. Alternatively, the outputs of flow meters Si and 83 can be lperiodically read and the corresponding warmup factor manually calculated.

Warmup factors determined by the method of this invention compare fairly closely vwith those determined from the ASTM distillation. However, because the continuously determined warmup factor is based on continuous isothermal distillations rather than on the batch ASTM distillations, some discrepancy in warmup factor may exist. The magnitude of this discrepancy can be determined by comparing the measured warmup factor with the warmup factor determined from an ASTM distillation performed on the same test material. if the magnitude of this discrepancy is larger than the desired precision allows, the measured val-ue can be corrected by applying an appropriate correction factor to the calculated value of warmup factor. This correction factor can be programmed into the computer so that the computer output indicates the corrected value of warmup factor.

On stream calibration check of the analyzer is made by analyzing a standard sample of known warmup factor. Referring again to FIGURE l, the normal test sample is obtained from sample source 7l which can be a tank,

blended product line, etc. Standard sample is maintainedl in sample source 72 which can be a container of any convenient type. Sample feed line 70 can be connected to test sample source '7l or standard sample source 72 by means of three way valve 75 and connecting lines 73 and 74. Valve 7S can be switched manually, or is conveniently remotely controlled where the analyzer is located at a distance from the blender control. Calibration of the analyzer can thus be conveniently checked as frequently as necessary during an actual blending operation.

Although a preferred embodiment of analyzer is described in FIGURE 1, several modifications can be made in the apparatus in addition to those previously described. For example, rather than employing insulated housings and internal heaters, the housings can be submerged in a heated bath maintained at the appropriate distillation temperature. Overhead volume ow rate recorders 2d, 44 and 66 are primarily used to troubleshoot problems in the analyzer and can be deleted. Similarly the recording feature of flow controllers Zo, de and 69 can be deleted. In another modification, condensers 23, d3 and 63 can be deleted and the overhead product metered in the vapor phase. This embodiment is not preferred as condensation of the vapors, which are at their dew point, must be prevented, and because the measured quantity of vapor ow must be converted to a liquid volume ow rate for utilization in the warmup factor computation. In another embodiment the vapors are combined and then condensed by passage through a single condenser prior to measurement of the volume dow rate. Additionally, the analyzer apparatus can be installed on a rack or within an appropriate housing depending upon the type of installation required.

Other embodiments of the analyzer, not illustrated, comprise alternative modes of measuring the various vol- Cil urne flow rates necessary for computing the warmup factor. Under steady state conditions, the total of the volume ow rate of sample fed to distillation units 10, 30 and 50 is equal to the sum of the total liquid overhead and residue fractions from each of the distillation units. Accordingly, the flow determinations necessary for the computation of warmup factor can be made by physically measuring any two of these flow rates. For example, the necessary flow data can be obtained by measurement of the total volume ow rate of feed to each of the co1- umns and either the volume dow rate of total overhead fraction or total liquid residue. The total feed volume flow rate can be determined by summation of the individual column feed rates measured by ow controllers Ztl, d and 69, or the total flow can be measured by installing an additional How meter in combined sample line 70 upstream of branch line 13. Similarly, the total volume flow rates of overhead fraction and liquid residue can be obtained by summation of individually measured flow rates or by measurement of the volume flow rate of the combine-d overhead and residue streams as metered by flow meters S3 and 81, respectively.

FIGURE 2 is a simplified flow diagram of a blending system for producing a multicomponent blended liquid product having a predetermined warmup factor, which system is particularly adapted to the blending of gasoline. FIGURE 2 primarily shows the adaptation of the continuous warmup factor analyzer of this invention to automatic control of a continuous inline blending process. In this process, any number of stock components, identihed as stocks A through N, are admixed in controlled proportions to produce a blended product having a controlled warmup factor. The proportion of stocks in the blend is varied as necessary to achieve a desired warmup factor. In varying the composition to control warmup factor, it is essential that other characteristic properties be maintained within specification limits or at optimum values. Needless to say, at least one of the component stocks must have a warmup factor below that desired for the liquid product and at least one of the component stocks must have a warmup factor below that desired for the liquid product and at least one of the component stocks must have a warmup factor above the target value.

Referring now to FIGURE 2, stock component A is pumped from source 169 through component line 101 to blended product line i3d by pump 102 at a rate controlled by metering and control device w3. Similarly, stocks E and N are pumped from sources llo and lli) through component lines lll and llZl to blended product line 139 by pumps lli and l2?. at rates controlled by metering and control devices 113 and l23, respectively. Blended product is discharged through blended product line 130. Any number of component blending systems can be employed in the method of this invention. Stocks A, B and N are representative of any number of separate liquid components. in the case where the blended product is gasoline, these stocks can represent gasoline stocks, liquid dye solution, corrosion inhibitors, additives, and anti-knock fluids such as tetraethy lead and tetramethyl lead. Fhe above blending method is generally illustrative of many conventional continuous inline blending schemes. Stochr sources it), M0 and 12() can be storage tanks, pipelines, tank cars, tank trucks, drums, weigh tanks or other devices for storage of liquid materials. pumps i162, i12 and l2?. can be deleted where the individual stocks are under suiiicient pressure or at sufficient hydrostatic head to cause them to flow to product line 13d without additional energy.

Metering and control devices w3, 17.3 and l23 represent any means for controlling the proportion of each stock in the final blend and having an automatically adjustable set point. In the simplest case, a conventional flow ratio controller responsive to differential pressure across an orifice plate or venturi is located in each component line. Each of these controllers receives a signal proportional to the flow of blended product in line 134)` and each controls the flow of individual stocks according to a preset ratio by throttling a flow control valve in the appropriate component line. The ratio setpoints of one or more of the control devices is automatically adjusted by the output signal from warmup factor analyzer 132, either directly or through a cas-cade control system. However, this simple ratio control method is not sufficiently accurate for close blending jobs, such as the production of a blended gasoline product. Improved accuracy can be achieved by mechanical or electronic proportioning systems wherein the flow of each stock is more accurately determined by means of positive displacement or turbine type meters, and wherein the proportion of each stock is controlled according to predetermined values. Again, at least one of the stocks has an automatically adjustable proportional control reset by the output signal from warmup factor analyzer 132 so that the proportion of volatile sto-ck is controlled to yield a blended product having a predetermined warmup factor.

A preferred control scheme is illustrated in FIGURE 2. Blended liquid product is withdrawn from product line 130 and passed via sample line 131, to warmup factor analyzer 132. Warmup factor analyzer 132 is substantially as described previously and as illustrated in FIG- URE l. The warmup factor of the `sample is measured. A signal proportional to the measured value of the warmup factor is transmitted from analyzer 132 to master computer 133 via signal transmission line 134. Similarly, input signals proportional to the metered component flow rates are received into master controller 133 from metering and control devices E63, H3 and 123 via signal transmission lines 164, 114 and 124, respectively. Master computer 33 can be of the digital or analog type wherein the measured input variables are received, and a new composition calculated, either continuously or periodically. Desired, or target, values of warmup factor and other limitations are programmed into the computing system. The deviation of warmup factor and other controlled variables from target values are determined and a new composition computed to obtain the desired properties. Signals proportional to the desired value of the various components in the blend are transmitted from master computer 133 to metering and control devices 163, 113 and 123 via signal transmission lines 165, 115 and 125, respectively. These signals serve as set point values to adjust the set points of the various control devices so as to produce a blended product having a composition controlled to yield a desired warmup factor and also other characteristic properties. Additional analyzers can be employed to measure these other characteristic properties and to transmit signals proportional to the measured property to master computer 133. The control mode can be either electric or pneumatic, or combinations of these two.

While a particular apparatus for continuously measuring the warmup factor of a multicomponent liquid mixture, and particular methods of analysis and of continuously -blcnd'mg a liquid product to a controlled warmup factor have been described, it will be understood that the invention is not limited thereto since many modifications in the method and apparatus can be made, and it is intended to include within the scope of the invention any such modifications as fall within the scope of the claims.

The invention having thus been described, I claim:

1. An apparatus for continuously measuring the warmup factor of a volatile liquid, which comprises:

first isothermal distillation means for continuously disfilling a first sample portion of said liquid at a constarrt feed rate and at a first controlled temperature `so as to obtain a first overhead fraction and a first liquid residue;

second isothermal distillation means for continuously distilling a second sample portion of said liquid at said constant feed rate and at `a second controlled temperature so as to obtain a second overhead fraction and a second liquid residue;

third isothermal distillation means for continuously distilling a third sample portion of said liquid at said constant feed rate and at a third controlled temperature so as to obtain a third overhead fraction and a third liquid residue; and

flow measuring means for measuring at least two of the variables of (l) the total of the volume flow rates of said first, second and third sample portions fed to said first, second and third distillation means, (2) the total of the volume flow rates of said first, second and third overhead fractions, and (3) the total of the volume ow rates of said first, second and third liquid residues.

2. The apparatus defined in claim 1 wherein said flow measuring means are adapted to measure the total of the volume flow rate of said first, second and third sample portions and the total of the volume flow rates of said first, second and third liquid residues.

3. The apparatus defined in claim 1 wherein said flow measuring means are adapted to measure the total of the volume flow rates of said first, second and third sample portions and the total of the volume flow rates of said first, second and third overhead fractions.

4. The apparatus defined in claim 1 wherein said flow measuring means are adapted to measure the total of the volume ow rates of said first, second and third overhead fractions and the total of the volume flow rates of said first, second and third liquid residue fractions.

5. An apparatus for continuously measuring the warmup factor of a volatile liquid, `which comprises:

first isothermal distillation means for continuously distilling a first sample portion of said liquid at a constant feed rate and at a first controlled temperature so as to obtain a rst overhead fraction and a first liquid residue;

second isothermal distillation means for continuously distilling a second sample portion of said liquid at said constant feed rate and at a second controlled temperature so as to obtain a second overhead fraction and a second liquid residue;

third isothermal distillation means for continuously distilling a third sample portion of said liquid at said constant feed rate and at a third controlled temperature so as to obtain a third overhead fraction and a third liquid residue;

an overhead conduit in communication with said first,

second and third distillation means adapted to receive said first, second and third overhead fractions and to transport the combined overhead fractions;

a liquid residue conduit in communication with said first, second and third distillation means adapted to receive said first, second and third liqud resdues and to transport the combine liquid residue;

combined overhead fiow measuring means for measuring the volume flow rate of combined overhead fraction flowing within said overhead conduit; and

combined residue ow measuring means for measuring the `volume flow rate of combined liquid residue flowing within said residue conduit.`

6. The apparatus defined in claim 5 including:

means for generating a first analog signal proportional to the volume flow rate of said combined overhead fraction;

means for generating a second analog signal proportional to the volume flow rate of said combined liquid residue; and

an analog computer adapted to simultaneously receive said first and said second analog signals and to continuously compute said Warmupfactor by dividing the product of 300 times said first analog signal by the sum of said first and said second analog signals.

7. The apparatus defined in claim 6 wherein said analog computer generates an analog signal proportional to the computed value of said warmup factor.

8. An apparatus for continuously measuring the warmup factor of a volatile liquid sample which comprises:

rst, second and third externally insulated housings defining first, second and third elongated vertical chambers;

means for continuously introducing first, second and third sample portions of said liquid into said first, second and third chambers, respectively, at controlled equal volume flow rates;

a heating means located in the bottom of each of said first, second and third chambers to maintain the temperature within said chambers at preset values;

an overhead conduit;

first, second and third means for withdrawing vapor from the top of said first, second and third chambers, respectively, said means communicating with said overhead conduit;

a liquid residue conduit;

rst, second and third means for withdrawing liquid residue from the bottom of said first, second and third chambers, respectively, at liquid withdrawal rates regulated to maintain a liquid reservoir in each of said chambers;

combined overhead flow measuring means for measuring the volume fiow rate of combined overhead fraction in said overA ead conduit; and

combined residue fiow measuring means for measuring the volume fiow rate of combined liquid residue in said liquid residue conduit.

9. The apparatus defined in claim 8 wherein said first, second and third means for withdrawing vapor from said chambers each include a condenser for condensing said withdrawn vapors.

10. The apparatus defined in claim 8 including:

means for generating a first analog signal proportional to the volume fiow rate of said comlbined overhead fraction;

means for generating a second analog signal proportional to the volume fiow rate of said combined liquid residue; and

an analog computer adapted to simultaneously receive said first and said second analog signals and to continuously compute said warmup factor by dividing the product of 300 times said first analog signal by the sum f said first and said second analog signals.

11. The apparatus defined in claim 10 wherein said analog computer generates an analog signal proportion] to the computed value of said warmup factor.

12. The method of measuring the warmup factor of a volatile liquid, which comprises:

continuously distilling a first sample portion of said liquid at a controlled constant feed rate and at a first constant temperature so as to obtain a first overhead fraction and a first liquid residue;

continuously distilling a second sample portion of said liquid at said controlled constant feed rate and at a second constant temperature so as to obtain a second overhead fraction and a second liquid residue;

continuously distilling a third sample portion of said iquid at said controlled constant feed rate and at a third constant temperature so as to otbain a third overhead fraction and a third liquid residue;

combining said first, second and third overhead fractions to obtain a combined overhead fraction;

combining said first, second and third liquid residues to obtain a combined liquid residue;

measuring the volume flow rate of said combined overhead fraction; and

measuring the volume flow rate of said combined liquid residue fraction.

13. The method defined in claim 12 including the step of condensing said overhead fractions prior to measurement of said volume fiow rates.

14. The method defined in claim 12 wherein said first temperature is F., said scond temperature is 210 F., and said third temperature is 250 F.

15. The method defined in claim 12 including the steps of generating a first analog signal proportional to the volume flow rate of said combined overhead fraction and a second analog signal proportional to the volume iiow rate of said combined liquid fraction and also including the additional step of continuously computing said warmup factor by dividing the product of 300 times said first analog signal by the sum of said rst and second analog signals.

16. The method defined in claim 15 including the step of generating an analog output signal proportional to the computed value of said warmup factor.

17. A method of continuously producing a blended liquid product having a predetermined controlled warmup factor, which comprises:

simultaneously combining a plurality of liquid components at volume flow rates controlled to maintain the proportion of each component in the blend at a selected value, at least one of said Components having a warmup factor below the warmup factor of said liquid product and at least one of said components having a warmup factor above the warmup factor of said product;

continuously measuring the warmup factor of said blended product; and

adjusting the proportion of components in said blended liquid product to maintain said warmup factor at said predetermined value. 1S. A method of blending a plurality of liquid components of varying volatilities to continuously produce a liquid product having a predetermined controlled warmup factor, which comprises:

simultaneously transferring each of said liquid components from a liquid component source to acommon product conduit at volume fiow rates controlled to maintain the proportion of each component in the blend at selected values, at least one of said components having a warmup factor below the warmup factor of said liquid product and at least one of said components having a warmup factor above the warmup factor of said product; continuously withdrawing a sample of said blended liquid product from said product conduit;

continuously distilling a first portion of said sample at a controlled constant feed rate and at a rst constant temperature so as to obtain a first overhead fraction and a first liquid residue; continuously distilling a second portion of said sample at said controlled constant feed rate and at a second constant temperature so as to obtain a second overhead fraction and a second liquid residue;

continuously distilling a third portion of said sample at said controlled constant feed rate and at a third constant temperature so as to obtain a third overhead fraction and a third liquid residue;

combining said first, second and third overhead fractions to obtain a combined overhead fraction; combining said first, second and third liquid residues to obtain a combined liquid residue;

measuring the volume flow rate of said combined overhead fraction;

generating a first analog signal proportional to said volume fioW rate;

measuring the volume fiow rate of said combined liquid residue;

generating a second analog signal proportional to said volume fiow rate;

continuously computing the warmup factor of said liquid product by dividing the product of 300 times said first analog signal by the sum of said first and second analog signals; and

adjusting the proportion of components in said blended liquid product to maintain said warmup factor Of said liquid product at a predetermined value.

19. The method defined in claim 18 including the additional step of generating an analog signal proportional to the measured warmup factor of said liquid product.

20. The method dened in claim 19 wherein said proportion of components in said blended liquid product is automatically adjusted responsive to said analog signal proportional to said warmup factor of said sample.

References Cited UNITED STATES PATENTS 3/1966 Rhodes et al 202-160 4/ 1966 Luther 73-613 WILLIAM F. ODEA, Pi'z'maly Examiner.

D. J. ZOBKIW, Assistant Examiner. 

17. A METHOD OF CONTINUOUSLY PRODUCING A BLENDED LIQUID PRODUCT HAVING A PREDETERMINED CONTROLLED WARMUP FACTOR, WHICH COMPRISES: SIMULTANEOUSLY COMBINING A PLURALITY OF LIQUID COMPONENTS AT VOLUME FLOW RATES CONTROLLED TO MAINTAIN THE PROPORTION OF EACH COMPONENT IN THE BLEND AT A SELECTED VALUE, AT LEAST ONE OF SAID COMPONENTS HAVING A WARMUP FACTOR BELOW THE WARMUP FACTOR OF SAID LIQUID PRODUCT AND AT LEAST ONE OF SAID COMPONENTS HAVING A WARMUP FACTOR ABOVE THE WARMUP FACTOR OF SAID PRODUCT; CONTINUOUSLY MEASURING THE WARMUP FACTOR OF SAID BLENDED PRODUCT; AND ADJUSTING THE PROPORTION OF COMPONENTS IN SAID BLENDED LIQUID PRODUCT TO MAINTAIN SAID WARMUP FACTOR AT SAID PREDETERMINED VALUE. 